How to import a grease pencil draw into another grease pencil file?
Anyone trying to import grease pencil drawing into another grease pencil file:

Click File --&gt; Append
Select the Grease Pencil File you want to import --&gt;
A new menu of directories pops up, select COLLECTION --&gt;
A new list of collections pops up --&gt; select COLLECTION again.
Done, your Grease Pencil object should now be &quot;in&quot; another Grease Pencil canvas.



Additional resources on stackexchange. They did not help me, but might help you:
How do i copy material from one .blend file to another?
How can I reuse existing materials, objects, etc from an existing .blend?

Reference:
How To Import Grease Pencil Object